Our laboratory has focused on factors that influence host responses to tumors and may adversely influence responses to immunotherapy. We have identified an immunoregulatory factor produced by a variety of human tumors that profoundly inhibits in vitro cell mediated immune responses. We are in the process of characterizing and purifying this factor and also determining its role in vivo. We are developing sensitive new techniques to measure humoral immune responses to human tumor-associated antigens including an enzyme-linked immunabsorbent solid-phase assay using soluble and membrane bound human tumor-associated antigens. Using monoclonal antibodies, we are analyzing the distribution of tumor associated antigens on primary tumors and their metastases. Concurrently, we have established a murine melanoma model with cloned primary and metastatic cell lines to test various therapeutic options. We are preparing hybridoma monoclonal antibodies to human and murine tumor-associated antigens in an attempt to develop specific serotherapy for metastatic tumors.